The present invention relates to a battery of primary or secondary electrochemical cells that includes electrical contact elements to pass electricity and to enable information concerning the characteristics of the battery to be collected. These contact elements are designed to co-operate with a connector carried by an external application to which the battery is to be connected, e.g. a piece of telecommunications equipment.
A battery is made up of a plurality of electrochemical cells connected in series and/or in parallel and assembled together in a common container. In general, a battery has common terminals respectively of positive and of negative polarity that are used for electrically powering an appliance external to the battery. Other information may be needed to enable the battery to operate properly, in particular its temperature or the state of charge of its cells. This information is obtained by measuring directly or by collecting information that has been stored. The information is transmitted to the external appliance via contact elements that enable links to be established.
Document EP-0 349 473 describes a battery having a container through which the terminals pass. A connector for connecting the terminals to a plurality of pluggable cables is integrated with or secured to the container, preferably by being embedded in the plastics material of the battery container. When the connector is integrated in the cover, it is held between the top portion and the bottom portion of the cover. It can also be inserted in a housing provided in the side wall and held in place by a catch.
In that case, common current inlet and outlet is provided by conventional type terminals connected to a connector which serves to increase the possible number of connections. A drawback of such a battery lies in the problem of fixing the additional connector so that it is held securely, and in the resulting bulk.
Document DE-4 406 079 describes a storage cell container made up of a bottom box and a base carrying a male connector for making a connection either to a charger or to a machine tool.
However in certain particular applications, the batteries need to be immersed. It is essential for the battery and for the connector to be leakproof. Wherever a component is integrated on the outside there is always a source of risk for overall sealing.
Document GB-2 183 081 relates to a leakproof container for receiving and protecting a battery. The cover of the container has two terminals constituting male pieces suitable for engaging the female ends of the terminals of the battery. The terminals of the container can be connected to coupling connectors.
The container placed around the battery pointlessly adds volume and additional weight, and that is usually not desired by users.
In addition, the connectors used in those known batteries are standard commercial components for a variety of uses such that their very versatility makes them complex. As a result they are not exactly suited to battery manufacturers and their cost is found to be excessive.
An object of the present invention is to propose a battery capable of being connected to an external application, where the cost of manufacturing the battery is reduced and where the battery is closely matched to user requirements.
Another object of the invention is to provide a battery whose sealing in the event of immersion is more reliable.
The present invention provides a battery of electrochemical cells placed in a container of insulating material having at least one wall carrying a terminal unit for connecting said battery to an external application, wherein said terminal unit is a leakproof female terminal unit constituted by a body of insulating material having sockets, said body being integrally formed with said wall, the terminal unit also comprising partially hollow contact elements of tubular shape and of outside diameter no greater than 2.9 mm, said elements being placed in said sockets and sealing between said body and said elements being provided by a resin.
The insulating material is selected from polyamides, polyolefins such as polyethylene (PE) or polypropylene (PP), polystyrenes, polycarbonates, polyphenylene oxide (PPO), and acrylonitrile/butadiene/styrene (ABS) copolymers.
The insulating material is preferably polyamide 6xe2x80x946. Its characteristic, in particular its mechanical, chemical, and electrical characteristics, correspond to those desired. Its use is advantageous because of the ease with which it can be molded and its low cost.
In an embodiment of the invention, said insulating material further contains a reinforcing agent. Said reinforcing agent is preferably constituted by glass fibers.
Preferably, said insulating material is polyamide 6xe2x80x946 containing 30% by weight of glass fibers.
The battery of the invention has a female type terminal unit whose contact elements are tubular in shape and partially hollow. The tubular elements have a hollow section at each end for receiving at one end connection pieces coming from the battery and at the other end pluggable pins belonging to a suitable male connector. Because of the clearance that exists between the contact element and the wall of the housing, the hollow ends have a certain amount of flexibility which makes plugging easier.
Advantageously, the contact elements are provided with an annular external shoulder. When the connector element is put into place in the socket passing through the insulating body of the terminal unit, the shoulder comes to bear against a step formed on the inside wall of the socket. Under such circumstances, somewhat more clearance can be provided.
The battery is sealed at said terminal unit by resin which is inserted into the inside portion of the terminal unit fitted with said contact elements that are electrically connected to the electrochemical cells. The shoulder then serves as a barrier preventing the resin from escaping to the outside. It is also used to determine accurately the quantity of resin that is required. When the element does not have a shoulder, then the viscosity of the resin in association with the small amount of clearance between the element and the wall of the housing prevents the resin from penetrating beyond the desired limit.
Furthermore, the connection between said terminal unit and a connector connected to said application is sealed by means of a gasket surrounding the outside of said terminal unit and against which said connector comes to bear. The gasket is preferably received in a housing provided for that purpose. During plugging, the insulating body of the connector comes into contact with the portion of the terminal unit where the gasket is placed.
The present invention also provides a method of manufacturing the above-described battery, in which method said wall and said insulating body are made simultaneously by molding, preferably by injection molding.
An advantage of the present invention is that it makes it possible to avoid the problem of inserting and fixing a connector to the battery container both in terms of support and in terms of sealing the interface. The method of manufacture is thus shortened and simplified since the number of parts and the number of assembly operations is reduced. Battery manufacture is cheaper and more reliable.